NETW320 Converged Networks
Professor: Patrick Price
Week 2 Assignment: Silence Suppression
May 18, 2014
What is Silence Suppression?
Silence suppression, also called voice activation detection (VAD) is used with VoIP to save on bandwidth. It is, “a software application that allows a data network carrying voice traffic over the Internet to detect the absence of audio and conserve bandwidth by preventing the transmission of ‘silent packets’ over the network” (Rouse, 2008). During a phone conversation, usually only one side is talking at a time so the other side is listening. Without silence suppression, that silence was still being transmitted. So when using silence suppression, the use of bandwidth can be reduced up to 50% for voice calls. However, even with active silence suppression, “there is still data being sent, and some sound can be heard by the user at the other end of the line. That sound, however, will only approximate the sounds a microphone is picking up at the other end of the conversation” (What Is Silence Suppression). Then there is also a, “comfort noise generation (CNG) that generates background noise for voice communications during periods of silence that occur during the course of the conversation” (Rouse, comfort noise generator (CNG), 2007).
Why is it used?
It is used because it very advantageous for business, especially ones that don’t have a lot of bandwidth on their networks because their networks won’t be clogged as much when using silence suppression. Voice transmission is more sensitive than data so not having enough bandwidth can cause, “voice distortions, breaks and jumps between words, which could make effective communication all but impossible for the individuals trying to use it” (What Is Silence Suppression).
What could be used instead of silence suppression?
The only alternative I found to silence suppression is not to use it. There are some drawbacks to using silence suppression including clipping...
Bibliography: A. Xie, R. K. (2007, January). RFC 4788 Enhancements to RTP Payload Formats for EVRC Family Codecs. Retrieved May 21, 2014, from IETF: http://tools.ietf.org/html/rfc4788
Rouse, M. (2007, September). comfort noise generator (CNG). Retrieved May 21, 2014, from TechTarget: http://searchtelecom.techtarget.com/definition/comfort-noise-generator-CNG
Rouse, M. (2008, March). voice activation detection (VAD). Retrieved 05 21, 2014, from TechTarget: http://searchunifiedcommunications.techtarget.com/definition/voice-activation-detection
What Is Silence Suppression. (n.d.). Retrieved May 21, 2014, from wiseGEEK: http://www.wisegeek.com/what-is-silence-suppression.htm
Zopf, R. (2002, September). RFC 3389 Real-time Transport Protocol (RTP) Payload for Comfort Noise (CN). Retrieved May 21, 2014, from IETF: http://tools.ietf.org/html/rfc3389
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